Linux Kernel f2fs sysfs OOB & Integers >4b
CVE-2026-23235 Published on March 4, 2026
f2fs: fix out-of-bounds access in sysfs attribute read/write
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix out-of-bounds access in sysfs attribute read/write
Some f2fs sysfs attributes suffer from out-of-bounds memory access and
incorrect handling of integer values whose size is not 4 bytes.
For example:
vm:~# echo 65537 > /sys/fs/f2fs/vde/carve_out
vm:~# cat /sys/fs/f2fs/vde/carve_out
65537
vm:~# echo 4294967297 > /sys/fs/f2fs/vde/atgc_age_threshold
vm:~# cat /sys/fs/f2fs/vde/atgc_age_threshold
1
carve_out maps to {struct f2fs_sb_info}->carve_out, which is a 8-bit
integer. However, the sysfs interface allows setting it to a value
larger than 255, resulting in an out-of-range update.
atgc_age_threshold maps to {struct atgc_management}->age_threshold,
which is a 64-bit integer, but its sysfs interface cannot correctly set
values larger than UINT_MAX.
The root causes are:
1. __sbi_store() treats all default values as unsigned int, which
prevents updating integers larger than 4 bytes and causes out-of-bounds
writes for integers smaller than 4 bytes.
2. f2fs_sbi_show() also assumes all default values are unsigned int,
leading to out-of-bounds reads and incorrect access to integers larger
than 4 bytes.
This patch introduces {struct f2fs_attr}->size to record the actual size
of the integer associated with each sysfs attribute. With this
information, sysfs read and write operations can correctly access and
update values according to their real data size, avoiding memory
corruption and truncation.
Products Associated with CVE-2026-23235
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Affected Versions
Linux:- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below e85a99db9ab85dfc30d93b0ca0e9156f3127f55a is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below 438a405fbad6882df0e34b3e1a16839a71f04240 is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below 6a6c07a9b49e43f0df42d7118fc76aa555c73d98 is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below eebd72cff518ac87e660aefb8a41224bd88c32ce is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below 4ef30b9f1641c9e877792df6b049f1cf507d002d is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below d4a594dd952df123cbdcdee9b9640d9d55e4a954 is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below 3a905e183c047577b154f08a78ac3039e9454703 is affected.
- Version b59d0bae6ca30c496f298881616258f9cde0d9c6 and below 98ea0039dbfdd00e5cc1b9a8afa40434476c0955 is affected.
- Version 3.12 is affected.
- Before 3.12 is unaffected.
- Version 5.10.251, <= 5.10.* is unaffected.
- Version 5.15.201, <= 5.15.* is unaffected.
- Version 6.1.164, <= 6.1.* is unaffected.
- Version 6.6.127, <= 6.6.* is unaffected.
- Version 6.12.74, <= 6.12.* is unaffected.
- Version 6.18.13, <= 6.18.* is unaffected.
- Version 6.19.3, <= 6.19.* is unaffected.
- Version 7.0-rc1, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.